1. Field of the Invention
The present invention relates to a display device provided with a display unit displaying information.
2. Description of the Related Art
A music playback device, such as a CD player, which plays back music includes a display unit such as an LCD (Liquid Crystal Display) and a fluorescent display tube, and the music playback device acts as a display device that displays information (for example, see Japanese Patent Publication Laid-Open No. 2013-152327). As illustrated in FIG. 11A, the display unit included in the music playback device displays a track number of the music and a title of the music such that a user easily selects the music to be played back. As illustrated in FIG. 11B, the display unit also displays information indicating how much volume (magnitude of sound) is set to the music playback device. In order to reduce cost of the music playback device, sometimes the track number of the music, the title of the music, and the volume cannot be displayed at one time in case that a small display unit is used. Therefore, sometimes a track number+ title display mode in which the track number of the music and the title of the music are displayed as illustrated in FIG. 11A and a volume display mode in which the volume is displayed as illustrated in FIG. 11B are switched. The music playback device includes a display switching key used to receive operation to switch the display mode, a track-up key used to receive operation to increase the track number, and a playback stopping key used to receive operation to stop the playback of the music. At this point, for example, the display mode is switched in the case that the operation of the display switching key is received.
FIG. 12 is a view illustrating a functional block of a microcomputer included in the music playback device. As illustrated in FIG. 12, a microcomputer 100 acts as an information storage 101, a music playback processor 102, a display switching key processor 103, a track-up key processor 104, a playback stopping key processor 105, and a display processor 106. The microcomputer 100 acts as each unit (software module) by an independent program, and each unit transmits and receives an instruction and information through inter-module communication indicated by an arrow. A technique of developing the program while dividing the program into functional modules is frequently adopted in order to increase productivity.
The track number and title of the music, the track number of the currently playing-back music (hereinafter, also referred to as a “current track number”), the current volume, and the current display mode are stored in the information storage 101. The track number and title of the music are stored in the information storage 101 while correlated with each other. At this point, in the case that the music is not currently played back, namely, in the case that the playback is held, the current track number stored in the information storage 101 becomes the track number of the music to be played back. The music playback processor 102 plays back the music. The music playback processor 102 changes the currently playing-back music to the music corresponding to the next track number in response to an instruction from the track-up key processor 104 described later. At this point, the music playback processor 102 acquires the track number of the next music to be played back from the information storage 101. The music playback processor 102 stops the playback of the music in response to an instruction from the playback stopping key processor 105 described later.
Then, processing operation performed by the display switching key processor 103 will be described with reference to a flowchart in FIG. 13. The display switching key processor 103 performs the following processing operation when receiving the operation of the display switching key 201. The display switching key processor 103 acquires the current display mode from the information storage 101 (S101). The display switching key processor 103 determines whether the acquired current display mode is the volume display mode (S102). In case of determining that the current display mode is the volume display mode (Yes in S102), the display switching key processor 103 sets the display mode from the volume display mode to the track number+ title display mode, and instructs the information storage 101 to update the display mode stored in the information storage 101 (S103). On the other hand, in case of determining that the current display mode is not the volume display mode, namely, that the current display mode is the track number+ title display mode (No in S102), the display switching key processor 103 sets the display mode from the track number+ title display mode to the volume display mode, and instructs the information storage 101 to update the display mode stored in the information storage 101 (S104). After the processing in S103 or S104, the display switching key processor 103 instructs the display processor 106 to update the display of the information (S105), and ends the processing.
Then, processing operation performed by the track-up key processor 104 will be described with reference to a flowchart in FIG. 14. The track-up key processor 104 performs the following processing operation when receiving the operation of the track-up key 202. The track-up key processor 104 acquires the current track number from the information storage 101 (S201). Then the track-up key processor 104 determines whether the acquired current track number is the final track number based on the track number stored in the information storage 101 (S202). For example, in the case that the track numbers are stored up to “10” in the information storage 101 while the current track number is “10”, the track-up key processor 104 determines that the current track number is the final track number. For example, in the case that the track numbers are stored up to “10” in the information storage 101 while the current track number is “5”, the track-up key processor 104 determines that the current track number is not the final track number. In case of determining that the current track number is the final track number (Yes in S202), the track-up key processor 104 ends the processing.
On the other hand, in case of determining that the current track number is not the final track number (No in S202), the track-up key processor 104 increases the current track number by one (for example, changes the current track number from “5” to “6”), and instructs the information storage 101 to update the current track number stored in the information storage 101 (S203). Then the track-up key processor 104 determines whether the music playback processor 102 currently plays back the music (S204). In case of determining that the music playback processor 102 currently plays back the music (Yes in S204), the track-up key processor 104 instructs the music playback processor 102 to play back the music corresponding to the next track number (S205). In response to the instruction, the music playback processor 102 changes the currently playing-back music to the music corresponding to the next track number. In case that the track-up key processor 104 determines that the music playback processor 102 does not currently play back the music (No in S204), or after the processing in S205, the track-up key processor 104 instructs the display processor 106 to update the display of the information (S206), and ends the processing.
Then, processing operation performed by the playback stopping key processor 105 will be described with reference to a flowchart in FIG. 15. The playback stopping key processor 105 performs the following processing operation when receiving the operation of the playback stopping key 203. The playback stopping key processor 105 determines whether the music playback processor 102 currently plays back the music (S301). In case of determining that the music playback processor 102 currently plays back the music (Yes in S301), the playback stopping key processor 105 instructs the music playback processor 102 to stop the playback (S302). In response to the instruction, the music playback processor 102 stops the playback of the music.
In case that the playback stopping key processor 105 determines that the music playback processor 102 does not currently play back the music (No in S301), or after the processing in S302, the playback stopping key processor 105 acquires the current track number from the information storage 101 (S303). The playback stopping key processor 105 determines whether the acquired current track number is “1” (S304). In case of determining that the acquired current track number is not “1” (No in S304), the playback stopping key processor 105 sets the track number to “1”, and instructs the information storage 101 to update the current track number stored in the information storage 101 (S305). This is because the track number “1” and the title corresponding to the track number “1” are displayed after the stopping of the playback. Then, the playback stopping key processor 105 instructs the display processor 106 to update the display of the information (S306), and ends the processing. On the other hand, in case of determining that the acquired current track number is “1” (Yes in S304), the playback stopping key processor 105 ends the processing because the track number “1” and the title corresponding to the track number “1” are displayed after the stopping of the playback based on the display information stored in the information storage 101.
Then, processing operation performed by the display processor 106 will be described with reference to a flowchart in FIG. 16. The display processor 106 performs display update processing in FIG. 16 in the case that each of the processors 103 to 105 instructs the display processor 106 to update the display of the information (S105, S206, and S306). The display processor 106 acquires the current display mode from the information storage 101 (S401). Then the display processor 106 determines whether the acquired current display mode is the volume display mode (S402). In case of determining that the current display mode is the volume display mode (Yes in 402), the display processor 106 acquires the current volume from the information storage 101 (S403). The display processor 106 updates the display of the volume to the acquired current volume (S404).
On the other hand, in case of determining that the current display mode is not the volume display mode (No in S402), namely, that the current display mode is the track number+ title display mode of, the display processor 106 acquires the current track number from the information storage 101 (S405). The display processor 106 updates the display of the track number to the acquired current track number (S406). The display processor 106 acquires the title corresponding to the acquired current track number from the information storage 101 (S407). The display processor 106 updates the display of the title to the acquired current title (S408).
As described above, when the track-up key 202 is operated, the track-up key processor 104 increases the track number by one, and causes the music playback processor 102 to play back the music corresponding to the next track number. At this point, when the current track number is the final track number (Yes in S202 of FIG. 14), the track-up key processor 104 does not perform the processing. That is, the track-up key processor 104 does not instruct the display processor 106 to update the display of the information. Even if the current track number is the final track number (Yes in S202 of FIG. 14), the track-up key processor 104 may instruct the display processor 106 to update the display of the information (Yes in 302 of FIG. 14, and processing S206). However, necessity to update the display is eliminated because the track number stored in the information storage 101 is not updated (the processing in S203 is not performed). The unnecessary processing increases a processing load on the microcomputer 100.
In order to suppress the processing load on the microcomputer 100, as illustrated in FIG. 14, the track-up key processer may instruct the display processor 106 to update the display of the information only in the case that the track-up key processor 104 instructs the information storage 101 to update the track number stored in the information storage 101, namely, only in the case that there is the necessity to instruct the display processor 106 to update the display of the information. However, when the track-up key processor 104 instructs the display processor 106 to update the display of the information, the program causing the microcomputer 100 to act as the track-up key processor 104 becomes complicated.
As described above, each of the key processors 103 to 105 instructs the display processor 106 to update the display of the information every time each of the operation keys 201 to 203 is operated. In the case that the display switching key processor 103 instructs to update the display of the information, because the display mode stored in the information storage 101 is updated from one of the display modes to the other display mode (S103 and S104), the display processor 106 updates one of the display modes to the other display mode (S404, S406, and S408). When the display mode is the volume display mode (Yes in S402), the display processor 106 updates the display of the volume (S404) even if the track-up key processor 104 instructs to update the display of the information. At this point, the unnecessary processing is performed, because the volume is not changed although the track number stored in the information storage 101 is updated while increased by one (S203). The unnecessary processing increases a processing load on the microcomputer 100.
In order to suppress the increase in processing load on the microcomputer 100, for example, it is possible that the track-up key processor 104 acquires the current display mode stored in the information storage 101, and the track-up key processor 104 does not instruct the display processor 106 to update the display of the information in the case that the display mode is the volume display mode. However, in this case, the program causing the microcomputer 100 to act as the track-up key processor 104 becomes complicated. In the case that the music playback device includes the large display unit in which the track number of the music, title of the music and the volume can concurrently be displayed, there is no necessity to switch the two display modes. In this case, because the track-up key processor 104 does not acquire the current display mode stored in the information storage 101 to determine whether the acquired current display mode is the volume display mode, there is the necessity to modify the program causing the microcomputer 100 to act as the track-up key processor 104. When the necessity to modify the program causing the microcomputer 100 to act as the track-up key processor 104 is generated depending on the display unit, flexibility of the program is degraded.
As described above, each of the key processors 103 to 105 performs the instruction to the display processor 106 to update the display of the information and the determination of the necessity to update the display of the information in order to suppress the increase in processing load on the microcomputer 100, which results in the problem that the program causing the microcomputer 100 to act as the each of the key processors 103 to 105 becomes complicated.